Biology Chapter 2 Flashcards

Questions and Answers

Does all life require the same essential elements?

False

Which of the following is a chemical reaction?

Making a hydrogen bond between a water molecule and a sugar molecule

Dissolving a lump of sugar in a cup of coffee

Melting ice

None of the above (correct)

What is the BEST explanation of what has occurred when Carbon-14 decays?

An ionic bond has formed

The resulting atom is still carbon-14

The resulting atom still has an unstable nucleus

The resulting atom is now a different element because the number of protons has changed (correct)

What happens when two atoms form a chemical bond?

A chemical bond forms when two atoms transfer or share outer electrons to complete their outer shells Signup and view all the answers

What do you predict to be the charge on ammonium?

+1 Signup and view all the answers

How many electron pairs are shared between carbon atoms in a molecule that has the formula C2H2?

3 Signup and view all the answers

What is a compound?

Compounds have at least two different elements. Signup and view all the answers

Which bond or interaction would be difficult to disrupt when compounds are put into water?

Covalent bonds between carbon atoms Signup and view all the answers

Cations have a _ charge and anions have a _ charge.

cation = positive; anion = negative Signup and view all the answers

A covalent bond is likely to be polar when:

One of the atoms sharing electrons is more electronegative than the other atom Signup and view all the answers

Define electronegative.

High tendency to attract electrons to itself. Signup and view all the answers

Define element.

Substance that cannot be broken down into a simpler substance by ordinary chemical reactions. Signup and view all the answers

Define essential elements.

The elements an organism needs to live and reproduce. Signup and view all the answers

Define trace elements.

Elements required by an organism in minute quantities. Signup and view all the answers

What is carbon's atomic number and mass number?

Atomic number = 6, mass number = 12 Signup and view all the answers

What is an allotrope?

Different physical forms of the same element. Signup and view all the answers

What is oxygen's atomic number and mass number?

Atomic number = 8, mass number = 16 Signup and view all the answers

Define atom.

The smallest unit of an element that still retains the properties of that element. Signup and view all the answers

What does the atomic number tell you?

<h1>of protons</h1> Signup and view all the answers

What does the mass number tell you?

<h1>of protons + neutrons</h1> Signup and view all the answers

Define ion.

Atom with a net electric (+ or -) charge. Signup and view all the answers

Define isotope.

Atoms of the same element that differ in the # of neutrons. Signup and view all the answers

Define radioisotopes.

An isotope that has an unstable nucleus. Signup and view all the answers

What is radiocarbon dating - C14 used for?

Used to estimate large time scale ages. Signup and view all the answers

The first electron shell can hold _ electrons, the second and third electron shells can hold _ electrons.

1st shell = 2; 2nd and 3rd shell = 8 Signup and view all the answers

What is the valence shell?

The outermost shell, determining the chemical properties. Signup and view all the answers

What is a valence number?

The number of electrons needed to be lost or gained to be stable. Signup and view all the answers

Define molecule.

Two or more atoms from same or different elements held together by valence shell electron interaction. Signup and view all the answers

When electron shells are full, atoms are ________.

Stable Signup and view all the answers

When electron shells are not full, ______________ occurs.

Interaction Signup and view all the answers

What are the three types of chemical bonds?

Ionic, covalent, hydrogen. Signup and view all the answers

Define ionic bonds.

Atoms bonded through attraction of oppositely charged particles (ions) - exchange of electrons. Signup and view all the answers

Define covalent bonds.

Atoms share valence electrons. Signup and view all the answers

Define polar covalent bonds.

Unequal sharing, causing a slight electrical dipole. Signup and view all the answers

Define non-polar covalent bonds.

Equal sharing; the charge is the same on both atoms. Signup and view all the answers

Any bond between two atoms of the same element forms a _________ bond.

Non-polar covalent bond Signup and view all the answers

Define free radical.

A molecule whose atoms have one or more unpaired electrons in their outer shells. Signup and view all the answers

What can you do to prevent free radical damage?

Take vitamins A and E and use antioxidant cream. Signup and view all the answers

Define hydrogen bonds.

Formed when partially positive hydrogen atoms in polar covalent bonds are attracted to partially negative atoms in another polar covalent bond. Signup and view all the answers

Are hydrogen bonds strong?

False Signup and view all the answers

List the three chemical bonds (ionic, hydrogen, and covalent) in order from strongest to weakest.

Covalent > Ionic > Hydrogen Signup and view all the answers

Chemical bonds hold _______ together and store .

Molecules, energy Signup and view all the answers

Chemical equations describe _ .

Chemical reactions Signup and view all the answers

In a chemical equation, reactants are written to the _ of the arrow and products are written to the _ of the arrow.

Reactants on the left, products on the right Signup and view all the answers

Define oxidation.

Chemical process in which an atom, molecule, or ion loses an electron(s). Signup and view all the answers

Define reduction.

Chemical process in which an atom, molecule, or ion gains an electron(s). Signup and view all the answers

An example of an oxidation-reduction reaction is ____________.

Rusting Signup and view all the answers

Two examples of redox in biological systems are _ and _______.

Glycolysis and cellular respiration Signup and view all the answers

Study Notes

Essential Concepts in Chemistry

All living organisms require essential elements, but not all share the same elements.
A chemical reaction involves changes in molecular structure, unlike processes like dissolving or melting.

Carbon-14 and Nuclear Transitions

Carbon-14, with 6 protons and 8 neutrons, is pivotal in carbon dating.
When a neutron converts to a proton, it changes the atom's identity, indicating a transformation into a distinct element.

Chemical Bonds

Atoms form chemical bonds by transferring or sharing outer electrons to achieve stable configurations.
Nitrogen, typically forming three bonds, has a +1 charge in ammonium due to forming four bonds with hydrogen.

Covalent and Ionic Bonds

Carbon in C2H2 shares three pairs of electrons through covalent bonds.
Covalent bonds, particularly those between carbon atoms, are resistant to disruption in water.
Cations carry a positive charge, while anions carry a negative charge.

Bond Polarities

A covalent bond becomes polar if one atom is more electronegative than the other, leading to an unequal sharing of electrons.
Electronegativity refers to an atom's tendency to attract electrons.

Elements and Structures

Elements cannot be broken down by ordinary chemical reactions and have unique properties, defined by their atomic structures.
Essential elements like oxygen, carbon, hydrogen, and nitrogen are crucial for life, while trace elements are needed in minute quantities.

Atomic Structure and Isotopes

The atomic number indicates the number of protons, and the mass number combines protons and neutrons.
Isotopes of an element differ in neutron count, with unstable radioisotopes undergoing decay.

Chemical Stability and Valence

Atoms are stable when their electron shells are full; interactions occur when they are not.
The valence shell determines an atom's chemical properties, and the valence number indicates electrons needed for stability.

Types of Chemical Bonds

Chemical bonds include ionic, covalent, and hydrogen bonds, arranged from strongest to weakest as: covalent > ionic > hydrogen.
Ionic bonds result from the attraction of oppositely charged ions, while covalent bonds involve shared electrons.

Molecular and Atomic Interactions

A molecule comprises two or more atoms held together by electron interactions.
Free radicals, which have unpaired electrons, are unstable and reactive, leading to potential cellular damage.

Reactions and Equations

Chemical equations depict reactions, with reactants on the left and products on the right.
Oxidation involves losing electrons, while reduction refers to gaining electrons. An example of a redox reaction is rusting.

Biological Significance

Processes like glycolysis and cellular respiration demonstrate oxidation-reduction reactions in biological systems, highlighting their importance in metabolism.

Protective Measures

To combat free radical damage, antioxidants such as vitamins A and E can be beneficial.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on the essential elements of life and chemical reactions with these flashcards from Biology Chapter 2. Challenge yourself with questions about Carbon-14 and its use in dating. Perfect for students looking to reinforce their understanding of biological concepts.